WASHINGTON - The Senate on Tuesday rejected the notion that it couldn't discipline itself, defeating a proposal to set up a new office to investigate possible ethics violations.

The proposal to create an Office of Public Integrity was defeated 67-30 as the Senate moved closer to a final vote on legislation to tighten rules and laws dealing with congressional contacts with lobbyists.

Opposition to the new office was led by members of the existing ethics committee, who insisted that the current system of self-policing was working fine and the proposed office would only duplicate their work.

It's “off-target and unnecessary,” said Sen. George Voinovich, R-Ohio, chairman of the six-member ethics committee. “It will simply replicate the tasks that the ethics committee does every day.”

Many advocates of lobbying reform, joined by clean government advocacy groups, have maintained that an independent ethics commission must be a key part of any ethics reform legislation. They say the ethics committees, particularly in the more partisan House, have proved incapable of addressing the lobbying scandals and ethical problems that have plagued Congress in recent years.

“It's very difficult for us to investigate ourselves,” said Sen. Susan Collins, R-Maine, chairman of the Senate Homeland Security and Governmental Affairs Committee and co-sponsor of the amendment with the committee's Democratic leader, Sen. Joe Lieberman, D-Conn.

The new office, she said, “would remove the cloud of doubt and suspicion that often hangs over members of Congress unfairly.”

With the approval rating of Congress down to about 25 percent, said Sen. John McCain, R-Ariz., “shouldn't we do what we can to fix either a real or imagined problem that we have with the people that we serve?”

Earlier this month, Collins' own committee also rejected the idea of the ethics office, reflecting the strong resistance to what some saw as an attempt to undermine the constitutional duty of lawmakers to set their own rules. Before the proposal went to the Senate floor, Collins altered it to reduce the powers of an ethics office, assuring that the ethics committee would retain authority over investigations and could overrule the office. The proposal was rejected nonetheless.

The Senate approved, by 84-13, a proposal offered by Sens. Ron Wyden, D-Ore., and Charles Grassley, R-Iowa, to end the practice of secret “holds” in which senators can single-handedly block action on legislation.